This invention relates to scanner devices in general and more specifically to a scanner optical imaging assembly mounted on a single circuit board with one or more edge mounted optical detectors.
Optical scanner devices are well-known in the art and produce machine-readable image data signals that are representative of a scanned object, such as a photograph or a page of printed text. In a typical scanner application, the image data signals produced by an optical scanner may be used by a personal computer to reproduce an image of the scanned object on a suitable display device, such as a CRT or a printer. Some examples of optical scanner devices are fax machines, digital copiers, and computer scanners (flatbed and portable).
Optical scanners are well-known in the art and various components thereof are disclosed in U.S. Pat. No. 5,552,597 of McConica for xe2x80x9cHand-Held Scanner having Adjustable Light Pathxe2x80x9d, U.S. Pat. No. 5,586,212 of McConica, et al., for xe2x80x9cOptical Wave Guide for Hand-Held Scanner,xe2x80x9d U.S. Pat. No. 5,381,020 of Kochis, et al., for xe2x80x9cHand-Held Optical Scanner with Onboard Battery Recharging Assembly,xe2x80x9d and U.S. Pat. No. 5,306,908 of McConica, et al., for xe2x80x9cManually Operated Hand-Held Optical Scanner with Tactile Speed Control Assembly,xe2x80x9d all of which are hereby incorporated by reference for all that they disclose.
A typical optical scanner may include an optical imaging assembly comprising illumination, optical, and detection systems. The illumination source illuminates a portion of the object (commonly referred to as a xe2x80x9cscan regionxe2x80x9d), whereas the optical system collects light reflected by the illuminated scan region and focuses a small area of the illuminated scan region (commonly referred to as a xe2x80x9cscan linexe2x80x9d) onto the surface of a photosensitive detector positioned within the scanner. The photosensitive detector converts the image light incident thereon into electrical signals representative of the scan line. Image data representative of the entire object then may be obtained by sweeping the scan line across the entire object.
The term xe2x80x9cimage lightxe2x80x9d as used herein refers to the light reflected from the document and focused onto the surface of the detector array by the optical system. The image light may be converted into digital signals in essentially three steps. First, the photosensitive optical detector converts the light it receives into a varying electric current. Second, the varying electric currents from the detector elements are converted into analog voltages by an analog amplifier. Finally, the analog voltages are digitized by an analog-to-digital (A/D) converter. The digital data then may be processed and/or stored as desired.
While optical scanners of the type described above are being used, they are not without their problems. Image quality, scanner size and cost, and ease of assembly are related to the design and complexity of the optical imaging assembly. For example, the various components of the imaging assembly, i.e., the illumination source, the optical system and the detection system, must be precisely aligned to properly illuminate the document and focus the image light onto the detectors. The position, orientation, and distance of each element with respect to other elements must be correct to within close tolerances. Furthermore, the imaging assembly must be robust enough to resist shifting when the optical scanner is jolted or the operating environment varies.
If the illumination source is not properly aligned, the scan region may be too dark and the resulting image may lack contrast. If the image light is not properly focused and directed onto the detectors, the resulting image may be blurry or dark. Complex mounting and alignment systems may be employed to address these problems. However, a complex imaging assembly results in a relatively large, costly, and error prone optical scanner. Furthermore, the more complex the imaging assembly, the more difficult it is to assemble, and the more likely elements are to shift out of alignment.
Highly complex imaging assemblies also have a large tolerance stack. It is impossible to manufacture each part to the exact design measurements, therefore each part has a design tolerance, or an acceptable amount of error in size or shape. As parts are placed next to each other during design, the tolerance of each is added to a tolerance stack. Therefore, when elements of the imaging assembly are separated by a relatively large number of parts, the tolerance stack between the parts is relatively large, and the alignment error may be large enough to reduce image quality.
A complex imaging assembly with a large number of parts also results in a large optical scanner which is very difficult to scale down.
Consequently, a need exists for a smaller imaging assembly which is simple to assemble and align, resulting in a lower cost. A need further exists for an imaging assembly having a reduced tolerance stack to improve alignment and simplify assembly or repair.
To assist in achieving the aforementioned needs, the inventor has devised an optical imaging assembly with at least one edge mounted optical detector which is smaller and which greatly simplifies assembly and alignment. This provides for smaller, lighter, and less expensive scanners in general.
The invention may comprise an optical imaging assembly having a mounting surface and at least one semiconductor die with a face and an edge portion. The edge portion of the at least one semiconductor die is mounted to the mounting surface. A light sensitive optical detector is located on the face of the at least one semiconductor die. An optical system is mounted to the mounting surface adjacent the at least one semiconductor die.
The invention may also comprise a method of producing an imaging system including providing at least one photodetector having a light sensitive face and an edge portion, connecting the edge portion of the at least one photodetector to a circuit board, and connecting a lens to the circuit board adjacent the at least one photodetector.
The invention may also comprise a method for assembling an optical imaging assembly. The method comprises providing at least one optical detector having a light sensitive face, an edge portion, and a first plurality of electrical contact pads placed adjacent the edge portion. The method further comprises providing a substrate having a second plurality of electrical contact pads corresponding to the first plurality of electrical contact pads. The method further comprises placing the edge portion of the at least one optical detector against the substrate, aligning the first plurality of electrical contact pads with the second plurality of electrical contact pads, and electrically connecting the first plurality of electrical contact pads to the second plurality of electrical contact pads.